The present invention relates to a water-in-oil emulsion antifoaming composition. In particular, a water-in-oil emulsion antifoam composition containing a nonionic surfactant, water and an antifoaming agent comprising hydrophobic silica in an oil carrier.
Antifoaming compositions are materials used in the prevention, removal and control of unwanted foam. Foamed fluids are dispersions of air or other gas as the discontinuous phase in a continuous liquid phase. Usually, since air or gas makes up the larger volume portion of such a foam, the bubbles are separated only by a thin liquid film. Unwanted fluid foams are made up of numerous tiny bubbles of a mechanical or chemical origin which are generated within a liquid and which rise and accumulate at the liquid surface faster than they decay.
The fields in which unwanted foams are encountered are very diverse, with problems ranging from unesthetic foams to foams which are hazardous to health. The problems associated with foaming are common in polymerization, paint processing and application, fermentation, sugar-refining, oil drilling and refining, food preparation , paper manufacture, sewage disposal, textile dyeing, textile printing ink pastes, adhesive application and conversion of ores refined by flotation. Moreover, liquid coolants, hydraulic fluids, lubricants, aviation fuels and gas adsorption fluids may foam with undesirable results under conditions of operation. If not properly controlled, foam can reduce equipment capacity and increase processing time and expense, as well as cause other disadvantages.
Although foam can be controlled by making basic changes in the process itself, or by using mechanical defoaming equipment, chemical antifoaming compositions have proven to be the most effective and economical. By adding a chemical antifoam composition to the system, stabilized films are broken, causing the foam bubbles to decay, and thus substantially or completely defoaming the system.
Among the many chemical compositions which are known to be useful for the prevention and destruction of undesirable foams, some of the most effective and versatile antifoaming agents are antifoaming compositions comprising hydrophobic silica suspended in an organic carrier with a small amount of emulsifying material. For specific examples of these types of antifoaming compositions see U.S. Pat. No. 3,076,768, herein incorporated by reference. Other examples of antifoaming compositions can be found in U.S. Pat. Nos. 4,039,469 and 4,123,383 also incorporated by reference.
While the above antifoaming composition exhibits good antifoaming properties, they can be improved upon from the standpoint of performance and economics. The present invention is directed to an antifoaming composition having improved properties. In particular, the antifoam composition of the present invention has improved properties when used in defoaming of aqueous systems in general.